immune cells

(noun)

White blood cells, or leukocytes, are cells of the immune system involved in defending the body against both infectious disease and foreign materials.

Related Terms

Examples of immune cells in the following topics:

  • Types of Adaptive Immunity

    • The adaptive immune response is mediated by B and T cells and creates immunity memory.
    • There are two subdivisions of the adaptive immune system: cell-mediated immunity, and humoral immunity.
    • Cell mediated immunity is controlled by type 1 helper T-cells (Th1) and cytotoxic T-cells.
    • Helper-T cells facilitate the immune response by guiding cytotoxic T-cells to pathogens or pathogen-infected cells, while the cytotoxic T-cells will kill the pathogens or pathogen-infected cells.
    • Humoral immunity refers to the component of the adaptive immune response that is caused by B cells, antibodies, and type 2 helper T-cells (Th2), as well as circulating mast cells and eosinophils to a smaller extent.

  • Cell-Mediated Immunity

    • Cell-mediated immunity involves cytotoxic T cells recognizing infected cells and bringing about their destruction.
    • Just as the humoral immune response has B cells which mediate its response, the cellular immune response has T cells, which recognize infected cells and destroy them before the pathogen inside can replicate and spread to infect other cells.
    • Cytotoxic T cells mediate one arm of the cellular immune response
    • The TH lymphocytes function indirectly to tell other immune cells about potential pathogens, while cytotoxic T cells (TC) are the key component of the cell-mediated part of the adaptive immune system which attacks and destroys infected cells.
    • Lymphocytes of the adaptive immune response must interact with antigen-embedded MHC class II molecules to mature into functional immune cells.

  • Lymphoid Cells

    • A lymphocyte is a type of white blood cell in the immune system.
    • T and B lymphocytes are the main forces of adaptive immunity, which includes cell-mediated and humoral immunity.
    • T cells are involved in cell-mediated immunity whereas B cells are primarily responsible for humoral immunity.
    • There are two types of T-cells involved in adaptive, cell-mediated immunity.
    • B cells are part of the humoral component of adaptive immunity.

  • Classes of T Cells

    • T cells play a central role in cell-mediated immune response through the use of the surface T cell receptor to recognize peptide antigens.
    • Cellular immunity is mediated by T lymphocytes, also called T cells.
    • This type of immunity promotes the destruction of microbes residing in phagocytes, or the killing of infected cells to eliminate reservoirs of infection.
    • Another class of T cells called regulatory T cells function to inhibit immune response and resolve inflammation.
    • Their major role is to shut down T cell-mediated immunity toward the end of an immune reaction.

  • Type IV (Delayed Cell-Mediated) Reactions

    • Cell-mediated immunity is an immune response that does not involve antibodies, but rather involves the activation of phagocytes, natural killer cells (NK), antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen.
    • Historically, the immune system was separated into two branches: humoral immunity, for which the protective function of immunization could be found in the humor (cell-free bodily fluid or serum) and cellular immunity, for which the protective function of immunization was associated with cells.
    • Therefore in cell mediated immunity cytokines are not always present.
    • 3. stimulating cells to secrete a variety of cytokines that influence the function of other cells involved in adaptive immune responses and innate immune responses
    • Cell-mediated immunity is directed primarily at microbes that survive in phagocytes and microbes that infect non-phagocytic cells.

  • Specific T-Cell Roles

    • The different categories of T cells are the basis for cell-mediated immune system activity.
    • T helper cell assist other white blood cells in immunologic processes by facilitating cytokines that activate and direct other immune cells.
    • The secondary immune response mediated by memory T cells is much faster and more effective at eliminating pathogens compared to the initial immune response.
    • Their major role is to shut down T cell-mediated immunity toward the end of an immune reaction and to suppress auto-reactive T cells that escaped the process of negative selection in the thymus.
    • Natural killer T cells (NKT cells – not to be confused with natural killer cells) bridge the adaptive immune system with the innate immune system.

  • Antigen-presenting Cells: B and T cells

    • There are two types of adaptive responses: the cell-mediated immune response, which is controlled by activated T cells, and the humoral immune response, which is controlled by activated B cells and antibodies.
    • The two types of lymphocytes of the adaptive immune response are B and T cells .
    • Upon antigen binding to a B cell receptor, a signal is sent into the B cell to turn on an immune response.
    • B cells are involved in the humoral immune response, which targets pathogens loose in blood and lymph, while T cells are involved in the cell-mediated immune response, which targets infected cells.
    • Explain the role played by B and T cells in the adaptive immune system

  • Overview of Adaptive Immunity

    • The adaptive immune system is composed of highly specialized, systemic cells and processes that eliminate or prevent pathogenic growth.
    • The adaptive immune system, also known as the specific immune system, is composed of highly specialized, systemic cells and processes that eliminate or prevent pathogenic growth.
    • The adaptive immune system starts to work after the innate immune system is activated.
    • Active immunity is generally long-term and can be acquired by infection followed by B cells and T cells activation, or artificially acquired by vaccines, in a process called immunization.
    • Helper T cells, or Th cells, coordinate immune responses by communicating with other cells.

  • Adaptive Immunity and the Immunoglobulin Superfamily

    • There are two types of adaptive immune responses: humoral immunity and cell-mediated immunity.
    • The interaction of antigens with membrane antibodies on naive B cells initiates B cell activation .
    • Members of the IgSF include cell surface antigen receptors, co-receptors, and co-stimulatory molecules of the immune system, molecules involved in antigen presentation to lymphocytes, cell adhesion molecules, certain cytokine receptors, and intracellular muscle proteins.
    • When a B cell encounters its triggering antigen, it gives rise to many large cells known as plasma cells.
    • Describe the role of immunoglobulins in the adaptive immune response, specifically in humoral immunity

  • Immunological Memory

    • During the adaptive immune response to a pathogen that has not been encountered before, known as the primary immune response, plasma cells secreting antibodies and differentiated T cells increase, then plateau over time.
    • A memory cell is an antigen-specific B or T lymphocyte that does not differentiate into an effector cell during the primary immune response, but that can immediately become an effector cell on re-exposure to the same pathogen.
    • This is known as the secondary immune response.
    • The result is a more rapid production of immune defenses.
    • The immune response to vaccination may not be perceived by the host as illness, but still confers immune memory.